Visit The Home Depot to buy Headwaters in. x in. x in. Concrete Patio Pier Block PIERBLOCK.Block USA in. x in. x in. Precast Concrete Pier Block Gray color. Compression strength of , PSI. Weighs lb. Concrete. THD SKU .A deck pier block is in many ways just a simplified version of a “precast foundation”, a foundation type recognized by building codes. They’re subject to all the same requirements as a typical footing, regardless of not being cast in place..Above ground deck piers are precast, tapered concrete blocks with a wide base that are intended to rest directly on the ground or a concrete base..